| 摘要 |
<p>PURPOSE:To erase write data efficiently by providing an additional memory cell array which requires the significant difference irradiation amount of ultraviolet rays more than the minimum irradiation amount of a standard memory cell array because of write data erasure. CONSTITUTION:The additional memory cell array 7 is increased locally in thickness by, for example, 30%. Cells in a memory cell array 1 requires a drain- source voltage VPP, e.g. 21 volts (V) and a control gate-source voltage VCC, e.g. 5V for writing, but the additional memory cell array 7 requires the VPP and a control-gate high operating voltage VHH, e.g. 10V, and the minimum ultraviolet- ray irradiation amount required for erasure increases from conventional 7WS/ cm<2> to 10WS/cm<2>. When an additional control circuit 8 is enabled with the VHH, an incorporated operational amplifier 80 compares the VHH with the VCC to send out an inhibition signal to a row decoder 4a. Consequently, close erasure control corresponding to the erasure characteristics of a PR-OM piece is performed.</p> |
